Short strides or long strides when running

That is normal. You changing the muscles used and your legs are 'numb' from the bike. On shorter Tris, it is fine and you can go with it. On longer Tris with longer runs, you really have to hold back because you will run the first few miles fast, and then your legs will wake up and you get in trouble.

This is what has happened to me anyway...Unless your above average

Your results aren't that unusual for a run coming off the bike.  As I'm sure you have read, your mind plays tricks on you based on what it has seen on the bike, it relays that you are moving slowly and you need to pick up the pace and your body responds in kind.

With regards to your strides I can't help you much.  I've always been a glider (short steps) instead of a gazelle (long strides) as I find the impact on my joints is greatly reduced at a smaller step higher cadence running style.

One word of caution.  I don't know how long your first triathlon is but just be careful no to empty your tank on the front half of your run.  It's easy to do which is why you need to make the conscious effort to slow your body down.  It may be a pace you can maintain for 2 or 3 miles but if you are running a minute or two faster per mile than you normally train I would say eventually it is going to catch up with you on the course.  Perhaps not, but I speak from experience on this one.

Either way good luck to you in your race, and welcome to the addiction.

I've seen coaches advocate a target of 3 strides per second and shorten your stride length.

Thanks for the info.  I am doing a sprint so it is only a 5k run.  I will have to wait until race day to see how I feel and then push it based on how fresh I feel coming off the bike.  I was originally hoping to just be able to hold a 9:00/mile pace, but all my training has shown me that I can go much faster than that.  Just hope that I am in one of those "feel good" modes on race day. 

I follow the Good Form Running technique

3 steps a second with shorter steps to land on the midfoot to utilize the arch.  Even if you have flat or larger arches it is ideal.

http://www.goodformrunning.com/

the question isn't about stride length, but rather cadence.  how many steps per minute (or second).  The target for most people is right about 180 steps/min (3/second).  It may feel weird at first, and won't make you instantly faster, but it will help you get your feet under you, be more efficient (eventually) and less pounding on your body.

It's not that important whether your foot hits heel first, or not, but where it hits relative to your center of motion.  If your feet are hitting out in front of you- every step is 'stopping' you a little bit.  It's also shocking your body more than necessary.

But I believe what you are experiencing is common.  you're all charged up coming off the bike and you hit the ground running at above your normal pace.  This is where a garmin watch and HR monitor come in handy.  I too have been surprised at my pace for the 1st quarter mile off the bike, until I settle in.  it's usually 'too fast'.

then again- you may not know how fast you really are!  that's what race day is all about.

I love that quote right there.  Thanks for all the replies everybody. 

I went out this morning and decided to try the shortened stride / higher cadence running without adding a bike ride before it.  it is definitely working for me.  My avg pace is normally 9:15 to 9:30ish and that is usually on a 3 to 4 mile run.  I went for a 5 mile run today and my pace over 5 miles averaged out to be 8:48/mile.   Definitely much faster than normal and I seemed to have a ton of energy left when I was finished.  Maybe I'm using less energy to run, as I seem to be much smoother when taking smaller strides and not bouncing as much.  Couldn't have happened at a better time.  My swim and bike have both been seeing gains recently and with my race coming up soon, seeing improvements in my run is just another thing to boost my confidence.